For example, Japanese Utility Model Application Publication No. S63-70275 describes a permanent magnet generator having a plurality of plate shape permanent magnets radially arranged on an outer circumference of a non-magnetic axis, and a magnetic pole formed by disposing a core, which has a fan shape in cross section, between the plate shape permanent magnets. The permanent magnet generator disclosed in Japanese Utility Model Application Publication No. S63-70275 has an object of reducing leakage of magnetic flux that passes between adjacent poles through the non-magnetic shaft, and a V-shaped notch portion is provided on an inner diameter side of the magnetic pole core.
However, in the permanent magnet generator (motor) as described above, the circumferential width of the magnetic core (core piece part) is smaller at an end portion on a radially inner side of the V-shaped notch portion. For this reason, a technical problem has been raised since the magnetic flux is saturated inside the magnetic pole core, and thereby the magnetic flux is easily leaked to the V-shaped notch portion side. Accordingly, in the permanent magnet generator as described above, the magnetic flux, which is leaked to a radially inner side of the magnetic pole core, could not be sufficiently reduced.